This invention relates generally to a closure system for a container that includes a cap and spout assembly for snap-on receipt by a container neck. More specifically, the present invention relates to a cap and spout assembly and a method for assembling the cap and spout assembly onto a container wherein the cap and spout assembly includes a snap-on tamper evident cap and a snap-on pouring spout.
Many types of closures for sealing onto a container neck are known that include a spout received onto the neck of a container and a cap for closure of the spout. Typically, the cap is threaded onto the spout, and the spout and/or cap is either threaded into the container neck finish or clamped around the container neck finish via a separate crimping ring. For example, U.S. Pat. No. 4,236,629 to Dwinell, U.S. Pat. No. 4,632,282 to Nagashima and U.S. Pat. No. 4,568,006 to Mueller, et al. disclose various crimping ring arrangements for clamping the spout onto the container neck, wherein the crimping ring is constructed of a malleable metal. One disadvantage of this type of closure is that the metal crimping ring cannot be recycled together with the various plastic components and, therefore, must be removed from each container prior to recycling. Another disadvantage is that an additional assembly step is required to assemble the crimping ring onto the spout prior to assembly of the cap.
As another example of a closure that seals onto a container neck, U.S. Pat. No. 5,004,126 to Klesius discloses a plastic closure for a plastic container that includes a frame cap adapted to be screwed onto an externally threaded container neck over a flexible pouring spout. The frame cap is frangibly attached to and integral with a screw-on ring adapted to be threaded onto the externally threaded container neck. One disadvantage of this type of closure is the possibility of breaking the frame cap from the screw-on ring during threading of the ring onto the container neck. Although a flexible web is provided between the cap and ring to absorb excessive threading forces, excessive radial forces beyond those accommodated by the flexible web can nevertheless still result during assembly of the cap and ring onto the container neck so as to break the frangible cap and ring attachment, thereby defeating its tamper-evident function. Also, in many applications the tolerances of the container neck are not tightly controlled and depending on the tolerance stack of the cap, spout and container neck, the spout may prematurely seat onto the container neck such that continued threading of the ring onto the container neck breaks the frangible cap and ring attachment.
Other closures that seal onto a container neck include a snap-on spout received onto the container neck and a cap threaded onto the container neck over the snap-on spout. For example, U.S. Pat. No. 4,917,270 to Simon discloses a closure device that includes a spout received into a groove provided on the container neck, wherein the spout resiliently deforms over the container neck during installation to seat in the groove. U.S. Pat. No. 5,108,009 to Davidson et al. and U.S. Pat. No. 4,706,829 to Li disclose other similar interlocking spout and container neck configurations. Still, there is always a need for an improved snap-on closure for universal use with a variety of spouts.
For example, both the Li and Davidson et al. closures include a stiff spout constructed of a relatively hard plastic that is molded to a fixed configuration. As such, the spout alone provides the necessary resilient interlocking force required to seal onto the container neck, so that the cap is not required to enhance the spout/container neck seal and can therefore be entirely removed from the container neck. Other more flexible spouts present additional sealing problems beyond those addressed by the Simon, Davidson, et al. and Li closures.
Considering the Davidson, et al. patent in greater detail, the FIG. 7 and FIG. 8 illustrations might appear to have some similarity to the present invention due in part to the arrangement of the components relative to the neck of the container. Additionally, the specification makes mention of a sealing ridge 113 which is provided on an upper end portion of the outer peripheral surface of the cylindrical wall 106. There are, however, a number of significant differences between the dispensing and measuring package disclosed in the Davidson, et al. patent and the present invention. First of all, the present invention is directed to the snap fit assembly of a spout-type closure onto a raised cylindrical neck of a plastic container. Unlike Davidson, et aI., the present invention does not threadedly install the outer cap onto the neck finish. The interior surface of the neck finish is a straight cylinder, without any modifications or shaping. Unlike the present invention, the Davidson, et al. package does not include a nestable and extendable pouring spout with a center portion externally threaded so as to receive a threaded cap. Further, the Davidson, et al. package does not include an outer ring which is snapped over an outer flange of the spout which in turn is snapped over the raised neck finish of the container. The Davidson, et al. package would appear to be a specifically styled disposable package for one product of one company. In contrast, the present invention is addressing the need for a snap-fit closure assembly which would be suitable for use with a variety of containers coming from different manufacturers.
To some extent, flexible pour spouts that are movable between a nested position and an extended position are more prone to leakage at the spout/container neck interface than are rigid spouts. As a result, flexible spouts typically require additional means for maintaining the spout/container neck seal when the cap is removed from the spout. See, for example, European Patent Application No. EPO 320 808 Al which discloses a spout having a U-shaped flange flexibly received over a conical container flange and a retaining ring flexibly received onto the spout. The spout is assembled onto the container neck prior to assembly of the cap. One drawback of this configuration is that the sequential assembly potentially leaves the contents of the container accessible to tampering or contamination. If the cap and spout are assembled together, too much force is required to assemble the cap and spout over the container flange since both the U-shaped flange of the spout and the ring of the cap must resiliently flex over the same container flange. If the cap and spout are constructed of a less resilient plastic to facilitate simultaneous assembly, the assembled cap and spout are then more prone to leakage at high internal container pressures.
Another drawback with other plastic closures which try to establish a liquid-tight interface is their tendency to turn in or relative to the container opening. This is likely to occur when the closure cap is threaded back onto the spout and is tightened in position. The tightening torque may be sufficient to overcome the "grip" of the closure on the container opening and thereby allows relative rotation between the two. Even if this relative rotation does not actually result in or signify leakage, it is a negative from the consumer's perspective as they believe such movement denotes a likelihood of leakage.
Therefore, a need exists for an improved closure for sealing receipt onto a container neck that overcomes the deficiencies of the above-described closures. Such a closure should provide improved sealing characteristics for high internal container pressures, such as that resulting from impact or dropping of the container, while still being easily assembled together onto the container neck. Preferably, the closure should be constructed entirely of plastic and easily molded to facilitate manufacturing. The closure should be tamper evident and also easily installed onto a container neck without risk of damage to the tamper evident means.
Over the past few years there has been a push toward designs in this general field of technology which are ecologically responsible. Customers of closure products often express a desire for designs which can be recycled. For example, all-plastic spouts and either all-plastic or all-metal containers have become the designs of choice. After reviewing the existing designs, it was learned by the present inventors that tighter tolerances for the particular container opening design are required. It was also discovered that existing manufacturers of these containers typically use different tooling designs and different processes to create the container opening which is intended to receive the closure spout. This has led to several different configurations now on the market for the same basic opening design. Ideally a closure spout designed for a particular opening design would be suitable for a proper fit and assembly with any of the different configurations which might be encountered in the marketplace. To date, this has not been a problem because the existing designs incorporate a metal crimp ring which creates the necessary seal. However, many customers would prefer to have an all-plastic spout/closure assembly for the benefits and advantages of the aforementioned recycling. An all-plastic design makes it much easier to recycle and this is becoming more important as companies become more sensitive to ecology issues.
The present invention provides an all-plastic, tamper-evident spout and cap combination which meets the current market needs in a novel and unobvious way. A unique sealing configuration enables the cap and spout to be preassembled and then snapped onto the container neck finish. The combination is suitable for container necks which have minor shape and tolerance variations.